Freedman: The Meaning of an Asterisk

By
Andrew Freedman

What do last year's abnormally warm year worldwide and Barry Bonds' home run record have in common?

They both may need an asterisk to signify that someone has been cooking the books.

When baseball slugger Bonds broke Hank Aaron's home run record last year, many in the baseball world sought to add an asterisk to his home run total to indicate the influence that steroids use may have had in powering all of those baseballs over ballpark fences. For Bonds, the asterisk would become a modern day "Scarlet Letter."

Along similar lines, in the climate arena one idea to signify the influence of man made climate change is for climatologists to attach an asterisk to record warm periods, such as 2007, which according to NASA tied with 1998 for the second warmest year in a century. Such an asterisk would note the influence that human emissions of greenhouse gases - Mother Nature's steroids - may have played in boosting the temperature to that level.

In both Bonds' case and with the weather, the asterisk is more accurately applied to a statistic of a longer period than an individual event. While the performance enhancing benefits of steroids may increase the odds of hitting a home run, it's difficult, if not impossible, to attribute a single home run to steroids use. It could just as easily result from "natural" factors such as Bonds' innate skills, weight lifting regimen, practice routine, etc. After all, Bonds hit home runs before he allegedly used steroids.

But over the course of a season and a career, the increasing odds of hitting a single home run from steroids should compound, so it's no stretch to attribute a portion of Bonds' home run totals to steroid use, especially since his home run numbers surged late in his career, which was exactly when he allegedly took the juice.

Extending this train of logic to weather, a single Barry Bonds home run is like a single record warm day, such as occurred last Wednesday when the temperature climbed to 74 degrees in Washington. While such record warmth might seem suspicious in light of the science linking warming with greenhouse gas emissions, the fickle nature of day-to-day weather prevents making such a direct connection.

Climate scientists point to increasing concentrations of greenhouse gases as the cause of long-term warming trends. The data showing the spike in such gases as carbon dioxide and methane are striking, and help drive home the point that the atmosphere today when new records are being set has a far different composition from that of several decades ago.

According to the United Nations Intergovernmental Panel on Climate Change (IPCC), global greenhouse gas emissions increased by 70 percent between 1970 and 2004. There is now more carbon dioxide and methane in the atmosphere than has been present for at least the past 650,000 years. These greenhouse gases, the IPCC found, have helped drive global average surface temperatures upwards by about one degree Fahrenheit during the past 100 years, especially within the past two decades.

These greenhouse gases may have increased the odds of having that warm day, but as with the lone home run, it's next to impossible to determine whether that daily record high was due to greenhouse gas emissions, entirely natural factors such as the presence of a Bermuda High, strong warm front, or myriad other weather variables that influence day-to-day variations.

In fact, the storm that brought the deadly tornadoes to the mid-South and the mild air to D.C. most likely would have occurred if there were fewer molecules of carbon dioxide in the air -- despite John Kerry's suggestion otherwise..

According to the Associated Press, if there was any longer term climate cycle at all to blame for the storm, meteorologists suspect the periodic ocean-atmosphere climate cycle of La Nina, not global warming.

There were warm days before the atmosphere was juiced with man-made greenhouse gases. But as the years trend warmer and warmer due to more and more warm days at the same time as greenhouse gases build-up, attributing warm years to greenhouse gases, at least in-part, becomes more and more defensible.

So, in my view, an asterisk for long-term climate records is justified, but not for daily weather records and I'm happy about that, on a more selfish level.

I get a great deal of satisfaction by knowing that the weather I'm experiencing on a particular day is going into the record books because it beat out a similar occurrence in, say, 1934. Then I can say to a friend: "Hey, it hasn't been this warm on this day since 1934! Crazy, right?"

But if a climate change asterisk were added, I'd have to say something that is far more confusing, irritating, and not altogether accurate based on current climate science.

This is an excellent column Andrew, my favorite of yours since you joined.

One point I would have added: focusing on single record-warm days, lone catastrophic weather events, or even a single or pair of abnormally warm winters, as evidence that human-induced climate change is in fact occuring could ultimately prove costly to those trying to raise awareness among the public and convince governments to take action. Even with a gradually-warming climate, we may still have brutally cold winters, winters filled with snow, and record cold days. When those days occur, the public and skeptical policy-makers will say: "where is your global warming now?" And what will "leaders" like John Kerry be able to say, when they themselves were attributing isolated days or events to global warming?

As you rightly observe, Andrew, long-term trends are what we should focus on. The question is: what is long-term in this context? As someone who has becomed more convinced of climate change by the scientific evidence that has been released (particularly by the IPCC) in just the past two years, I'm still skeptical of some reports. For example, the recent report linking western droughts to global climate change is based on 50 years of data. Is that sufficiently long-term? My gut tells me no. But my gut, like my head, was trained in politics, policy and law, not science.

So I look to scientists and leaders expert in climate change to help me understand. If they are grandstanding over singular weather events, or one record warm day, how can I believe what they tell me about "long-term" trends?

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Good article Andrew. Like the comparison. These winds today are feriocious. I live on the river in Spotsylvania and it feels like Im reliving Isabel winds without the storm. All our trash cans blew away. Powers Out. I wish we could get these winds in the middle of a blizzard.

Southside FFX: You raise a valid concern about the need to refrain from overstepping the boundaries of climate science regarding individual weather events. Ultimately, groups and individuals who hype up weather events as being global warming-related could get burned by it if their credibility is damaged. Interestingly, there is at least one study in the peer-reviewed literature showing that there may be a link between tornadoes and climate change, but it doesn't represent a consensus viewpoint.

I have one question though. With an increase in greenhouse gas emissions of 70%, i would think that every single record high would indeed be able to be attributed to global warming. While other factors such as the bermuda high that pumps in all the warm air from the south that you mentioned play the primary role, the added greenhouse gases may have been enough to put the temperatures into record territory. There will always be times or warmer then average and colder then average temperatures, it's just the colder periods might be a tad warmer than they would've been without anthropogenic effects and the warmer periods might be a tad bit colder (but still warm nonetheless).
I don't think greenhouse gases fluctuate from day to day but are more of a constant (with a very gradual increase) where as weather fluctuates greatly. so, it seems like all the day to day temperature fluctuations would be tweaked just a little bit higher because of the increased greenhouse effect. thus, all temperature readings are VERY SLIGHTLY related to climate change.

Anybody notice the beautiful oranges, yellows, grays, and blues with the early-morning sunrise in the east hitting the shelf and scud clouds with the front this morning....and the intense rainbow to the west. It was a sight.

"In fact, the storm that brought the deadly tornadoes to the mid-South and the mild air to D.C. most likely would have occurred if there were fewer molecules of carbon dioxide in the air -- despite John Kerry's suggestion otherwise."

Exactly. Winter tornadoes and severe storms in the South are nothing unusual...they happen every year near the Gulf Coast and in Florida. What WAS unusual, though, was the January outbreak in the upper Midwest a few weeks ago. That has not happened since January 1967.

JF: While it does seem as if all daily high temperatures would be affected by greenhouse gas-induced warming, the weather is just too naturally variable to be able to accurately determine what the manmade influence is on a daily basis. Thus, scientists look to longer term averages where the whims of the natural, daily weather patterns don't have as much of an impact in order to identify the signal of greenhouse gas-related warming.

Absent greenhouse impact, the early tornado event might have occurred, but with all the tornadoes down in Central IL and south. Tornadoes in Wisconsin during January and February are extremely rare, granted that we're talking about the extreme southeastern corner and warmest area in the state, down near Racine and Kenosha, south of Milwaukee, and right by Lake Michigan.

There's been a considerable amount of thunder snow in the southern half of Wisconsin in recent weeks. Thunderstorms with snow have been recorded from LaCrosse in the west through the Madison area and eastward to Milwaukee during these recent storm systems. There have also been two or three thundersnow events in and around Chicago during the past few weeks (per Tom Skilling and the WGN crew!). (Meanwhile WE tend to sit HIGH & DRY with one big rain event and numerous virga-to-sprinkle episodes.) We seem to be able to depend on one constant: RAIN whenever I have a dance! It's predicted again tomorrow evening for my Clarendon Ballroom swing outing.

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